This is a variant with 2 transfer functions from the FRA Frequency Response Analyzer project. Symbols, code, and examples can be found at this link:
Qspice/Projects/FRA Frequency Response Analyzer - Dual · KSKelvin-Github/Qspice
example6.TransferFunction-FRAanlyzer2KSK.qsch
Two linear transfer functions in series to demonstrate obtaining two transfer functions with a single FRA
example1.Buck-FRAnalyzer2KSK.qsch
One simulation to obtain V(out)/V(duty) and I(L1)/V(duty) transfer functions
